<sup>18</sup>F-PFPN PET: A New and Attractive Imaging Modality for Patients with Malignant Melanoma
Xiao Zhang, Mengting Li, Yongkang Gai, Jing Chen, Juan Tao, Yang Liu, Fan Hu, Wenyu Song, Tzu‐Chen Yen, Xiaoli Lan
Abstract
<sup>18</sup>F-FDG PET has limited diagnostic applications in malignant melanoma (MM). <sup>18</sup>F-PFPN is a novel PET probe with high affinity and selectivity for melanin. We conducted a clinical study with two aims, firstly to investigate the biodistribution and radiation dosimetry of <sup>18</sup>F-PFPN in healthy volunteers, and secondly, to examine the diagnostic utility of <sup>18</sup>F-PFPN PET imaging in patients with MM. <b>Methods:</b><sup>18</sup>F-PFPN was synthesized through a fluoro-for-tosyl exchange reaction. Five healthy volunteers were enrolled to investigate the biodistribution, pharmacokinetics, radiation dosimetry, and safety of the tracer. Subsequently, a total of 21 patients with clinically suspected or confirmed MM underwent both <sup>18</sup>F-PFPN PET/MR and <sup>18</sup>F-FDG PET/CT scans. Normalized maximum standardized uptake values of selected lesions were determined for both tracers and compared in patient- and lesion-based analyses. <b>Results:</b><sup>18</sup>F-PFPN has elevated radiochemical yield and was highly stable in vivo. In healthy volunteers, <sup>18</sup>F-PFPN was safe and well-tolerated and its effective absorbed dose was comparable to that of <sup>18</sup>F-FDG. In patient-based analysis, <sup>18</sup>F-PFPN uptake was higher than <sup>18</sup>F-FDG for both primary tumors and nodal metastases. In lesion-based analysis,<sup>18</sup>F-PFPN PET imaging could detect 365 metastases that were missed on <sup>18</sup>F-FDG PET. Additionally, <sup>18</sup>F-PFPN PET imaging had clinical value in distinguishing false-positive lesions on <sup>18</sup>F-FDG PET. <b>Conclusion:</b><sup>18</sup>F-PFPN is a safe and well-tolerated melanin PET tracer. In a pilot clinical study, <sup>18</sup>F-PFPN PET imaging outperformed traditional <sup>18</sup>F-FDG PET in identifying both primary MM and its distant spread.